Presently, the wireless communication has developed from the second generation(circuit-switched network) to the third generation(packet-switched network). In Korea, the wireless communication system was upgraded from CDMAone(IS-95A) to CDMAone(IS-95B) and now to CDMA 2000 1xRTT(IS-95C; hereinafter “CDMA 1x”). When data transmission rates of each system are compared with each other, the maximum data transmission rate of IS-95A is 14.4 Kbit/s, the maximum data transmission rate of IS-95B is 64 Kbit/s and the maximum data transmission rate of CDMA 1x, which called as a third generation communication system is 144 Kbit/s.
As a matter of fact, CDMA 1x is not regarded as third generation but rather 2.5 generation because data transmission rate of CDMA 1x is faster than IS-95A or IS-95B; however, it is insufficient for the third generation standard adopted by ITU.
FIG. 1 illustrates the architecture of CDMA network importing CDMA 1x EV-DO network.
To improve the data transmission rate of CDMA 1x network 20, CDMA 1x EV-DO(Evolution Data-only; hereinafter “EV-DO”) network 30 has been developed, and EV-DO network 30 is piled on the existing IS-95A/IS-95B network 10 and CDMA 1x network 20 for operation. EV-DO network 30 has 2.4 Mbit/s(minimum 600 Kbit/s) as maximum data transmission rate, and is a data transmission only network.
According to the import of EV-DO network 30 to CDMA 1x network 20, the existing CDMA 1x network 20 performs voice communication and EV-DO network 30 performs data communication. Accordingly, in order to perform the voice communication, an IS-856 mobile terminal that can operate on EV-DO network 30 has to periodically monitor a paging slot of CDMA 1x network by switching between existing CDMA 1x network 20 and EV-DO network 30. The paging slot monitoring starts when the mobile terminal operates in a slot mode.
Due to the periodical switching between CDMA 1x network 20 and EV-DO network 30(hereinafter “hybrid operation”), more power is consumed in the IS-856 mobile terminal than in the existing mobile terminal, and as a result, the standby time of the IS-856 mobile terminal becomes short.